Drive gearing for engine starters



Oct. 22V, 1940. v D. P. KEARNEY 2,218,972

DRIVE GEARING FOR ENGINE STARTERS Filed June 14; 1959 Z'Sheetssheet 1 Oct 22, 1'940- ,l D. P. KEARNEY n v2,218,972.

' DRIVE GEARIN-G Fon ENGINE sTAR'rEns v Fiied June 14, 1939 i 2 sheets-sheet 2v 63 l f :1I l. 65 56 Patented Oct. 1940 UNITED 1 srATEsj PATENT OFFICE 2,218,912 y DRIVE GEABING FOR ENGINE -STABTEBS Daniel l. Kearney, Birmingham,

Mich., assignor to Bendix Aviation Corporation; South Bend, Imi., a corporation of Delaware Application June 14, 1939, Serial No. 279,148

Claims.

10 ately toits idle position by the overrunning of the engine gearwhen the engine starts. Ii then the engine' should stall or stop for anyreason. it is necessary for the starting motor to come sub- A, stantially to rest and then be re-energized in order to secure re-en'gagementof the drive and resumption of the cranking operation.

It is an object of the present invention toprovide a novel starter drive of the type in which the gearing is automatically engaged by acceleration of the starting motor, which is simple in construction and efcient and reliable in operation.

It is another object to providevsuch a device which is arranged to maintain the engagement of the gearing as long as the starting motor remains energized irrespective of whether or not the engine becomes self-operative.

It is a further object to provide such a device incorporating provisions for permitting the engine l to overrun the drive withoutv causing disengagement thereof.

It is another object to provide suchva device which includes a self-tightening clutch connection between th e starting motor and pinion. It is anotherobject to provide such a device in which theengagement of the drive is maintained by speed-responsive means rotatable .with the starting motor.

Further objects andvadvantages will be apparent from the following description taken in connection lawith. the accompanying drawings in which: f Fig. 'l isa side elevation partly in section of a starter drive incorporating a preferred embodiment of the invention;

Fig. 2 is a similar view showing the parts in the positions assumed during the cranking operation;-

Fig; 3 is a section taken substantiallyl on the line 3-3 of Fig. l;

Fig. 4 is a section taken substantially on'theline 4-4 of Fig. 1;

Fig. 5 is a view similar to Fig. i of a second embodiment of the invention;

Fig. 6 is a similar view showing the parts in driving position; Fig. 'l is a section taken substantially 0n the line 1;-1 of Fig. 6, showing the parts in locked position; and y l Fig. 8 is a section taken substantially on the line 8 8 of Fig. 5.

In Fig. 1 of the drawings there is illustrated a 5 power shaft I which may be the extended armature shaft of a starting motor, not illustrated. A `piniori2 is slidably journalled on the power shaft for longitudinal movement into and out of enga'gement with a member 3 such as a flywheel 10 gear of an engine to be started.

A hollow sleeve 4 is fixed on the power shaft I by suitable means such as a key 5 and pin 6. Sleeve 4 is provided adjacent one end with an enlarged portion 1 having a non-circular or 15 double-D cross section, the remainder of the sleeve being cylindrical and threaded at its opposite end as .indicated at 8 for4 the reception of a stop nut 9. l

A screw shaft II is slidably journalled on the 20 sleeve 4 between the stop nut 9 and a shoulder I2 formed by the end of the enlarged portion 1 of the sleeve. Screw shaft II is provided with an enlarged head portion I3 of double-D cross section with a thrust shoulder- I4 adjacent .there- 25 to. Driving and driven anchor members I5 and I 6 in the form of discs or plates are provided with central openings I1 and I8 tting the double-D enlargements 1 and I3 of the sleeve 4 and screw shaft II respectively. The driving anchor mem- 30 ber I5 is confined on the enlargement or driving head 1 by means of a split lock ring I9, whilethe driven anchor member I6 bears against the shoulder I4 on the enlargement or driven head I3.

A. yielding transmission member in the form of 35 a spiral spring 2l is arranged to surround the driving and driven heads 1 and I3 and has e outturned ends '22 and 23 entering axial slots 24 and 25 in the anchor members I5 and I6 respectively so as to yieldingly connect said member/s 40 for rotation in unison while permitting longitudinal movement of the screw shaft II toward the driving head 1 until stopped by a' thrust washer 26-seated against the shoulder I2.

Means responsive to acceleration of the power 45 shaft I and consequently of the screw shaft II for moving the pinion 2 into operative engagement with the engine gear 3, is provided including a nut 21 threaded on the screw shaft, a barrel member 28 enclosing said nut and anchored as indicated 50 at v29 to the pinion 2, and a clutch plate 3l in the barrel'having peripheral lugs 32 slidably engaging. in slots 33 in the barrel and having a clutch 'surface 34 arranged to cooperate with a clutch surface 35 'on the nut 21. Means for coniining 55 the nut 21 and clutch plate 3| in the barrel are provided in the form of thrust washer 36 and a split lock ring 31.

An anti-drift spring 38 located between a.

ing in a slot 33 ofthe barrel. Ring 4I is arranged Y to wrap down and grip the nut when the nut tends to overrun the barrel. Ring 4I. also serves to transmit from the barrel to the nut a frictional rotative drag when the barrel overruns the nut. According to the present invention, means are provided for holding the pinion in its operative position responsive to rotation of the power shaft above a predetermined speed. As here shown, this means is in the form of a centrifugal latch 44 mounted in a longitudinal slot 45 in the screw shaft and anchored at one end within the driven head I3 as indicated at 46. 'I'he free end of the latch is provided with a tooth or projection 41 which normally conforms to a portion of the thread on the screw shaft II, but is movable by centrifugal force as shown in Fig. 2 to bring it into abutting relation with therear surface of the clutch nut 21.

i 'Ihe end of the latch 44 is preferably turned out and anchored in a hole 48 in the sleeve in order to position the latch longitudinally with respect to the sleeve. The slot 45 preferably terminates in an inclined or stepped wall 49 which is arranged to engage the free end of the latch 44 and limit the outward movement of the latch to the position illustrated in Fig. 2.

In the operation of the invention, starting with the parts in the positions illustrated in Fig.' 1, 40 rotation of the power shaft I by the starting motor is transmitted through sleeve 4 and spring 2| to the screw shaft II. Nut 21 is held from rotation by the control member 4I which is anchored in the barrel, whereby nut 21 is constrained to move longitudinally along the screw shaft, which motion is transmitted through the clutch plate 3| to the barrel 28 to move the pinion 2 into engagement with the-engine gear 3. When the clutch plate 3| engages the stop 5o nut 9, longitudinal movement thereof is arrested and the clutch nut 21 is caused to clamp the plate 3| against the stop nut and transmit rotation thereto.

When the engine starts, the accelerationv of the engine gear 3 causes the pinion 2 and barrel 28 to overrun the screw shaft II whereby the nut 21 is backed away from the clutch plate 3|, allowing the pinion, barrel and clutch plate to overrun. v If the engine continues self-operative,

overrunning of the barrel 28 causes a frictional drag through the spring ring 4| to be applied to the nut 21, tending to move it back to idle position. As long as the parts are rotating above a predetermined speed, however, the latch 44 is held out to its operative position as shown inl Fig. 2, preventing Abackward motion of the nut 21 and holding the parts in operative position. If the engine should not continue to be self-operative, therefore, the starting motor will resume the this occurs, the operator causesgthe starting motor to be deenergized, whereupon thepower shaft I and its associated parts slow down, and th`e latch J .Y

44 returns to idle position. Nut 21 is then traversed back to its idle position by the frictional 5 effect of the spring ring 4I, thus returning the pinion and barrel to their normal positions assisted by the anti-drift spring 38, in which poitions these latter parts may, continue to overrun until their rotary momentum is dissipated. l0

In Figs. 5 to 8 inclusive there is illustrated a second embodiment of the invention involving a re-location of the overrunning clutch, and a different form of centrifugal latch.

As here illustrated, a hollow sleeve 50 fixed to l5 the power shaft'5I has freely journalled thereon a screw shaft 52 yieldably driven from the hollow shaft by a yielding driving connection including a spring 53 in the same manner as inthe embodiment previously described. A control nut 54 is 20 threaded on the screw shaft 52 and is rigidly connected in any suitable manner with a barrel member 55. A stop nut 56 fixed on the end of the hollow shaft 50 acts as an abutment both for the screw shaft 52 and the control nut 54. An 25 anti-drift spring 51 normally maintains theA control nut 54 in its idle position as illustrated in Fig. 1.

A pinion 58 is freely journalled on the power shaft 5I and is connected to the barrel 55 by 30 means of an overrunning clutch which is arranged to provide for limited relative longitudinal movement. As here illustrated, the pinion 58 has an extended hub 59 to which is rigidly xed a flange member 6I having ratchet teeth 52 35 formed on one side thereof. A cooperating clutch ange 63 is formed onor rigidly mounted in the end of the barrel 55 and is provided with ratchet teeth 64 arranged to cooperate with the teeth 62 of clutch ange BI. A spring 65 0 mounted on the hub l, of the pinionI `bearing against the end of the barrel yieldingly maintains the clutch teeth 82, 84 in engagement but permits lthem to overrun when the pinion is accelerated with respect to the barrel. 45

Centrifugal means for opposing traversal of the control nut 54 back to its idle position, are provided in the form of a latch member 66 (Fig y '1) pivoted at B1 to the control nut 54 and having and barrel are rotating above a predetermined speed.

In the operation of this embodiment of the invention, starting with the parts in theV positions 60 shown in Fig. 5, energization of the power shaft 5| causes rotation of the screw shaft 52 in the direction of the arrow whereby the control nut 54 is traversed into engagement with the stop nut 58, thus moving the pinion 5 8 into mesh with 65 a memberl such as a flywheel gear 12 of an engine to be started.A Torque is thereupon transmitted from the screw shaft through the barrel 55 and clutch connection 64, 62 to the pinion 58 to crank the engine. 7b

When the engine starts, the acceleration of the engine gear 12 causes the pinion 58 to overrun the barrel 55 which is readily permitted by the overrunning clutch connection under the control of spring 65. Since at this time the screw shaft 52,

control nut El and barrel 55 are in rotation, the latch 66 is engaged against the shoulder 89 on the screw shaft and maintains the control nut I in its operative position as long as the power 5 shaftV 5I continues to be rotated by the starting motor.

When the operator opens the starting motor circuit, rotation of the power shaft, screw shaft, control nut and barrel ceases, whereupon the l0 latch 66 -is moved by the spring 'il into inoperative position, after which theY control n ut, barrel and pinion are permitted to be traversed back K to idle position by the frictional drag of the rotating pinion through the overrunning clutch connection wth the barrel, assisted by the action of the anti-drift spring 51.

It will thus be seen that in this embodiment of the invention asin the embodiment rst described, the starting pinion is maintained in mesh with the engine gear irrespective of overrunning thereof as long as the starting motor isv energized, premature demeshing being positively prevented by the centrifugal latch 68.

It will be understood that the invention is notY limited to the precise form of'overrunning connection shown, since any suitable form of overrunning clutch may be used if it is arranged to engage and drive positively and to release without sticking.

Although but two embodiments of the invention have been shown and described' in detail, it will be understood that other embodiments are possible and various changes may be made in the esgirandarra e ent of the partsvwithoiitgtie-fY parting from the spirit o e nventionnas defined in the claims appended hereto.

What is claimed is: l. In combination with a power shaft, an -engine starter drive mounted thereon including 40 a pinion slidable on the power shaft into and out of engagement with a member of the engine to be started, means responsive to acceleration of the power shaft for moving the pinion into l operative position, means including an overrunning clutch connection thereupon operative to rotate the pinion from the power shaft, said moving means being operative to return the pinion to idle position when the drive overruns the power shaft, and means responsive to the speed of rotation of the power shaft for holding the pinion in its operative position.

2. In combination with a power shaft, an engine starter driv'e mounted thereon including a pinion slidable on the power shaft into and out o f engagement with a membervof the engine to be started, means responsive to acceleration of the power shaft vfor moving the pinion into operative position, means including an overrunning clutch connection thereupon-operative to rotate the pinionA from the power shaft, said moving means being operative to return the pinion to idle position when the drivel overruns the power shaft, and a detent member mounted to rotate substantially at lthe same speed as the powerv 65 shaft, and movable by centrifugal force to engage an element of the pinion moving means and prevent return of the pinion to idle position.

3. I n an engine starter drive, a motor shaft, a

pinion movablethereon into and out of enga8- 70 ment with a member of an engine to be started,

actuating means for the pinion including a screw the n ut to the pinion, said driving connection including an overruning clutch, and a centrifugal detent rotatable with th'e screw shaft adapted to hold the pinion in engagement with the engine member. v

4. In an engine starter drive, a power shaft,

a pinion slidable thereon into andout of engagement with a member of an engine to be started, means .responsive to acceleration of the power shaft for moving the pinion into operative position and rotating the pinion, including a barrel member and an overrunning clutch between the barrel member and pinion, and centrifugal means rotatable with the barrel member for holding the pinion in operative position.

5. In an engine starter drive, a screw shaft, a nut threaded thereon, a pinio means including a barrel rigidly connected to the nut for moving the pinion into and out of engagement with a member of an engine to be started, an overrunning clutch connection between the barrel and pinion, means limiting longitudinal movement -of the nut in a direction to meshv the pinion, and means responsive to rotation of the nut for opposing returnv movement of the nutto idle position.

6. In an engine starter drive, a motor shaft, a pinion movable thereon into and out of engagement with a member of the engine vto be started, actuating means for the pinion'including a screwshaft rotatable with the1 motor shaft, a nut threaded on the screw shaft, a driving connec- 'tion between the nut and pinion for transmitting longitudinalhmovement from the nut to the pinion including an overrnning clutchforrotating the pinion from the nut, means limiting longitudinal `movement of the nut on the screw shaft in a direction tolcause engagement of the pinion with the engine member, thereby causing rotation of the nut with the screw shaft, and means 40 responsive to rotation' of the screw shaft above a predetermined speed for preventing movement of the nut back to idle position.

'7. In an engine starter drive, a motor shaft, a pinion; means responsive to acceleration of the 45 motor shaft for moving the pinion intov mesh with a member of an engine to be started in- Y cluding a self-tightening clutch, and a centrifugal detent rotatable with the motor shaft for -holding the pinion in mesh with the engine member.

8. In an engine, starter drive, a motor shaft, a pinion, means responsive to acceleration ofthe motor shaft for moving the pinion into mesh with a member of an engine to be started including 55 a screw shaft, a nut threaded thereon, and aselftightening friction clutch .betweenvthe nut and pinion, frictional control'mans for the clutch arranged to transmit torque from the pinion to the nut when the pinion overruns the screw shaft, 60'

to thereby cause traversal of the pinion and nut back to idle position, and centrifugalmeans rotatable with the screw shaft for holding the pinion in mesh with the engine member while the screw shaft is rotatingv above ,a predetermined a centrifugal detent mounted to rotate with the screw shaft, holding the nut and clutch plate adjacent the stop.

10. In an engine starter, a screw shaft, a. pin- 5 ion, means vactuating the pinion from the screw shaft including a nut-on the screw shaft, a barrel surrounding the nut connected to the pinion.

10 tudinal movement of the clutch plate., and an overrunning control clutch connecting the nut to the barrel arranged to grip and oppose overrunning of the barrel by the nut and also arranged to transmit torque frictionally from the barrel to the nut when the barrel overruns the nut, and a centrifugal detent rotatable with the screw shaft adapted `to engage the nut and prevent it from overrunning the screw shaft when the screw shaft is rotating above a predetermined speed.

DANIEL P. KEARNEY. 10 

